Flipped die stacks with multiple rows of leadframe interconnects

ABSTRACT

Stacked microelectronic packages comprise microelectronic elements each having a contact-bearing front surface and edge surfaces extending away therefrom, and a dielectric encapsulation region contacting an edge surface. The encapsulation defines first and second major surfaces of the package and a remote surface between the major surfaces. Package contacts at the remote surface include a first set of contacts at positions closer to the first major surface than a second set of contacts, which instead are at positions closer to the second major surface. The packages are configured such that major surfaces of each package can be oriented in a nonparallel direction with the major surface of a substrate, the package contacts electrically coupled to corresponding contacts at the substrate surface. The package stacking and orientation can provide increased packing density.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/971,384, filed on Dec. 16, 2015, the disclosure of which is herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The subject matter of this application relates to microelectronicpackages and assemblies in which a plurality of semiconductor chips arestacked one above the other and electrically interconnected with asupport element such as a package element or other circuit panel.

Description of the Related Art

Semiconductor die or chips are flat bodies with contacts disposed on thefront surface that are connected to the internal electrical circuitry ofthe chip itself. Semiconductor chips are typically packaged withsubstrates to form microelectronic packages having terminals that areelectrically connected to the chip contacts. The package may then beconnected to test equipment to determine whether the packaged deviceconforms to a desired performance standard. Once tested, the package maybe connected to a larger circuit, e.g., a circuit in an electronicproduct such as a computer, e.g., a server, among others.

Microelectronic packages can be fabricated which include semiconductorchips mounted on leadframes. Such packages can be incorporated in largerassemblies, typically as surface-mounted devices coupled to a circuitpanel. In order to save space certain conventional designs have stackedmultiple microelectronic elements or semiconductor chips within apackage. This allows the package to occupy a surface area on a substratethat is less than the total surface area of the chips in the stack.However, conventional stacked packages have disadvantages of complexity,cost, thickness and testability.

In spite of the above advances, there remains a need for improvedstacked packages and especially stacked chip packages which incorporatemultiple chips for certain types of memory, e.g., flash memory. There isa need for such packages which are reliable, thin, testable, and thatare economical to manufacture.

BRIEF SUMMARY OF THE INVENTION

In accordance with an aspect of the invention, a stacked microelectronicassembly can comprise a plurality of stacked encapsulatedmicroelectronic packages. Each encapsulated microelectronic package maycomprise a microelectronic element having a front surface which definesa plane, and a plurality of edge surfaces extending away from the planeof the front surface, the microelectronic element having a plurality ofchip contacts at the front surface. Each package has a plurality ofremote surfaces, and an encapsulation region contacting at least oneedge surface of the microelectronic element and extending in the firstdirection away from the at least one edge surface to a corresponding oneof the remote surfaces. The encapsulation region has a major surfacesubstantially parallel to the plane of the microelectronic element. Aplurality of electrically conductive package contacts are disposedadjacent a first plane defined by the first major surface and aplurality of second electrically conductive package contacts aredisposed adjacent a second plane parallel to the first plane anddisplaced therefrom. The first package contacts and the second packagecontacts are disposed at a single one of the remote surfaces, and thechip contacts are electrically coupled with the package contacts. Theplurality of microelectronic packages can be stacked one above anotherin the stacked assembly such that the planes of the microelectronicelements in each of the plurality of microelectronic packages areparallel with one another.

In accordance with one or more particular aspects, the first packagecontacts and the second package contacts of each package in the stackedassembly face and are electrically coupled with a corresponding set ofsubstrate contacts at a major surface of a substrate external to theencapsulation regions of each package of the stacked assembly, whereinthe major surface of the substrate is oriented non-parallel, e.g.,perpendicular to or tilted relative to the planes of the microelectronicelements in the stacked assembly.

The packages are stacked such that the first major surface of each nexthigher ordered package faces the second major surface of the next lowerordered package adjacent thereto. In accordance with a particularembodiment, a plurality of pairs of first and second package contactsare aligned and electrically coupled with one another, each paircomprising a first package contact of each next higher ordered packageand the second package contact of the next lower ordered package alignedand electrically coupled therewith.

In another example, the substrate contacts comprise a plurality of setsof substrate contacts, and each set comprises a plurality of the firstsubstrate contacts joined with the first package contacts of only one ofthe microelectronic packages via an electrically conductive bondingmaterial. A plurality of second substrate contacts can be joined withthe second package contacts of only the one microelectronic package viaan electrically conductive bonding material.

In one embodiment, each of the first package contacts and the secondpackage contacts of each package is a portion of a first leadframeelement or a portion of a second leadframe element, respectively, of acommon leadframe. The second leadframe elements can have first portionsinterdigitated among neighboring first leadframe elements, wherein thesecond package contacts are remote from the first portions and remotefrom the first leadframe elements. The second leadframe elements of atleast one of the packages may have bends between the first portions andthe second package contacts. In one embodiment, the common leadframe ofat least one of the packages further comprises a die attach pad, whereinthe microelectronic element has a face bonded to the die attach pad.

In one embodiment, at least one of the packages includes a firstmicroelectronic element, the face of the first microelectronic elementbonded to a first surface of the die attach pad, and includes a secondmicroelectronic element, the face of the second microelectronic elementbonded to a second surface of the die attach pad opposite from the firstsurface.

In one embodiment, at least one package includes a plurality of firststacked microelectronic elements including the first microelectronicelement, each first stacked microelectronic element overlying the firstsurface and electrically coupled with at least one of the first orsecond package contacts, and includes a plurality of second stackedmicroelectronic elements including the second microelectronic element,each second stacked microelectronic element overlying the second surfaceand electrically coupled with at least one of the first or secondpackage contacts.

In one embodiment, the stacked microelectronic assembly may furthercomprise third package contacts, wherein the first package contacts, thesecond package contacts and the third package contacts are portions offirst leadframe elements, second leadframe elements, and third leadframeelements, respectively, wherein immediately adjacent package contactsare spaced apart from one another in a direction orthogonal to the majorsurfaces of the package and the first package contacts are spacedfarther apart in the orthogonal direction from the third packagecontacts than from the second package contacts.

In one embodiment, each of the microelectronic packages has an identicalarrangement of the first package contacts and the second packagecontacts, wherein the packages comprise first packages each having afirst orientation, and second packages having a second orientationopposite from the first orientation, wherein at least some of the firstpackages are stacked immediately adjacent with at least some of thesecond packages among the stacked packages.

In accordance with an aspect of the invention, an encapsulatedmicroelectronic package can comprise a microelectronic element having afront surface defining a plane, a plurality of edge surfaces extendingaway from the plane of the front surface, and a plurality of chipcontacts at the front surface. The package may have a plurality ofremote surfaces, and an encapsulation region contacting at least oneedge surface of the microelectronic element and extending away from theat least one edge surface to a corresponding one of the remote surfaces,and the encapsulation region having first and second oppositely-facingmajor surfaces, each major surface being at least substantially parallelto the plane of the microelectronic element. A plurality of firstelectrically conductive package contacts may be disposed adjacent aplane defined by the first major surface and a plurality of secondelectrically conductive package contacts disposed adjacent a planedefined by the second major surface, the first package contacts and thesecond package contacts being disposed at a single one of the remotesurfaces, the chip contacts electrically coupled with the packagecontacts.

In one embodiment, each of the first package contacts and the secondpackage contacts of each package is a portion of a first leadframeelement or a portion of a second leadframe element, respectively, of acommon leadframe, the second leadframe elements having first portionsinterdigitated among neighboring first leadframe elements, the secondpackage contacts being remote from the first portions and remote fromthe first leadframe elements.

In one embodiment, the second leadframe elements of at least one of thepackages have bends between the first portions and the second packagecontacts. In one embodiment, the common leadframe may further comprise adie attach pad, wherein the microelectronic element has a face bonded tothe die attach pad.

In one embodiment, the microelectronic element is a firstmicroelectronic element, the face of the first microelectronic elementfacing toward a first surface of the die attach pad, the package furthercomprising a second microelectronic element, the face of the secondmicroelectronic element facing toward a second surface of the die attachpad opposite from the first surface.

In one embodiment, the microelectronic element may comprise first andsecond microelectronic elements, the faces of the first and secondmicroelectronic elements overlying and mechanically coupled with a firstsurface of the die attach pad.

In one embodiment, the microelectronic element may comprise a pluralityof the first microelectronic elements stacked and overlying the firstsurface and electrically coupled with at least one of the first packagecontacts or second package contacts, and comprises a plurality of thesecond microelectronic elements stacked and overlying the second surfaceand electrically coupled with at least one of the first package contactsor the second package contacts.

In one embodiment, the microelectronic package can have third packagecontacts, wherein the first package contacts, the second packagecontacts and the third package contacts are end portions of firstleadframe elements, second leadframe elements, and third leadframeelements, respectively, wherein immediately adjacent end portions arespaced apart from one another in a direction orthogonal to the majorsurfaces of the package and the first package contacts are spacedfarther apart in the orthogonal direction from the third packagecontacts than from the second package contacts.

In one embodiment, the plurality of first stacked microelectronicelements are stacked such that an edge surface of each first stackedmicroelectronic element is offset in a direction perpendicular to theedge surface from the edge surface of each first stacked microelectronicelement which is immediately beneath such first stacked microelectronicelement, and the plurality of first stacked microelectronic elements areelectrically coupled with the first package contacts and the secondpackage contacts via wire bonds.

In one embodiment, the first package contacts and the second packagecontacts do not extend more than 25 microns beyond a surface of theencapsulation region, the package further comprising a compliantmaterial disposed between first leadframe elements and at least some ofthe second leadframe elements at locations proximate to said remotesurface of the encapsulation.

In one embodiment, the second leadframe elements protrude beyond asurface of the encapsulation region by more than 50 microns.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view from above top and edge surfaces of amicroelectronic assembly according to an embodiment of the invention.

FIG. 2 is a perspective view from below the bottom and edge surfaces ofa microelectronic assembly according to an embodiment of the invention.

FIG. 3 is a side elevational view illustrating a microelectronicassembly according to an embodiment of the invention.

FIG. 4 is a partial enlarged side elevational view of a microelectronicpackage according to an embodiment of the invention.

FIG. 5 is a top-down plan view of an in-process structure according toan embodiment of the invention.

FIG. 6A is a bottom elevational view of a microelectronic assemblyaccording to an embodiment of the invention.

FIG. 6B is a bottom elevational view of a microelectronic assemblyaccording to a variation of the embodiment of the invention seen in FIG.6A.

FIG. 6C is a corresponding side elevational view of the microelectronicassembly according to the variation seen in FIG. 6B.

FIG. 6D is a bottom elevational view of a microelectronic assemblyaccording to another variation of the embodiment of the invention seenin FIG. 6A.

FIG. 7 is a bottom elevational view of a microelectronic assemblyaccording to an embodiment of the invention.

FIG. 8 is a side elevational view of a microelectronic assemblyaccording to an embodiment of the invention.

FIG. 9 is a side elevational view of a microelectronic package accordingto an embodiment of the invention.

FIG. 10 is a side elevational view of a microelectronic packageaccording to an embodiment of the invention.

FIG. 11 is a bottom elevational view of a microelectronic assemblyaccording to an embodiment of the invention.

FIG. 12 is a side elevational view of a microelectronic packageaccording to an embodiment of the invention.

FIG. 13 is a bottom elevational view of a microelectronic assemblyincorporating a plurality of packages according to an embodiment of theinvention as depicted in FIG. 12.

FIG. 14 is a side elevational view illustrating a microelectronicassembly according to an embodiment of the invention.

FIG. 15 is a side elevational view of a microelectronic packageaccording to an embodiment of the invention.

FIG. 16 is a side elevational view illustrating a microelectronicassembly according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

As used in this disclosure with reference to a dielectric region or adielectric structure of a component, e.g., circuit structure,interposer, microelectronic element, capacitor, voltage regulator,circuit panel, substrate, etc., a statement that an electricallyconductive element is “at” a surface of the dielectric region orcomponent indicates that, when the surface is not covered or assembledwith any other element, the electrically conductive element is availablefor contact with a theoretical point moving in a direction perpendicularto that surface of the dielectric region from outside the dielectricregion or component. Thus, a terminal or other conductive element whichis at a surface of a dielectric region may project from such surface;may be flush with such surface; or may be recessed relative to suchsurface in a hole or depression in the dielectric region.

As shown in the perspective views of FIGS. 1-2 and the correspondingside elevational view of FIG. 3, a microelectronic assembly 100 includesa package stack 110 which, in turn, includes a plurality of stackedmicroelectronic subassemblies or microelectronic packages 108, eachmicroelectronic package including one or more microelectronic elements112, at least one being a semiconductor chip. Microelectronic assembly100 and other microelectronic assemblies disclosed or referenced hereincan provide enhanced storage density which can be especiallyadvantageous in systems used in data centers, among which includeenterprise systems, government systems, hosted systems, search enginesystems, cloud storage, or other large-scale data centers.

Referring to the microelectronic package 108 according to the embodimentseen in FIG. 4, for example, each microelectronic element 112 can bearranged in a stack of similar microelectronic elements. In one example,each of the microelectronic elements may include a semiconductor chiphaving one or more memory storage arrays, which may include a particularmemory type such as nonvolatile memory. Nonvolatile memory can beimplemented in a variety of technologies some of which include memorycells that incorporate floating gates, such as, for example, flashmemory, and others which include memory cells which operate based onmagnetic polarities. Flash memory chips are currently in widespread useas solid state storage as an alternative to magnetic fixed disk drivesfor computing and mobile devices. Flash memory chips are also commonlyused in portable and readily interchangeable memory drives and cards,such as Universal Serial Bus (USB) memory drives, and memory cards suchas Secure Digital or SD cards, microSD cards (trademarks or registeredtrademarks of SD-3C), compact flash or CF card and the like. Flashmemory chips typically have NAND or NOR flash type devices therein; NANDtype devices are more common. Other examples of semiconductor chips areone or more DRAM, NOR, microprocessor, controller die, etc. orcombinations thereof. Each semiconductor chip may be implemented in oneof various semiconductor materials such as silicon, germanium, galliumarsenide or one or more other Group III-V semiconductor compounds orGroup II-VI semiconductor compounds, etc. The microelectronic elements112 in one or more microelectronic packages 108 and in one or morepackage stacks 110 may be a combination of different chipfunctionalities as described above and a combination of varioussemiconductor materials as described above. In one embodiment, amicroelectronic element may have a greater number of active devices forproviding memory storage array function than for any other function. Inone embodiment, a dummy spacer made from glass, silicon, or otherappropriate material can be positioned adjacent to or betweenmicroelectronic elements in a microelectronic package or subassembly.

Each microelectronic element can be a semiconductor chip having a frontsurface 114 defining a respective plane 116-x of a plurality of planes116-1, 116-2, etc. Each semiconductor chip 112 has a plurality ofcontacts 118 at its front surface and an edge surface 120 which extendsaway from the front surface of such chip. Each chip also has a rearsurface 122 opposite from its front surface 114. The front and rearsurfaces of adjacent microelectronic elements within a package may bebonded together with an adhesive (not shown). In one embodiment, theadhesive may be or include one or more layers of epoxy, elastomer,polyimide or other polymeric material. In some cases, a material used asa conformal dielectric coating over one or more of the microelectronicelements may also function as an adhesive. In one embodiment, suchconformal dielectric coating can be a polyxylylene material such ascommonly referred to as “parylene”. Parylene can also be used as a dieattach adhesive between adjacent microelectronic elements. In oneembodiment, one or more microelectronic elements may be packaged as afan-out wafer level package.

The chip contacts 118 on one or more microelectronic elements 112 in thepackage 108 are electrically coupled with package contacts disposed at aperiphery of the package. The package contacts of each package 108include first package contacts 127 and second package contacts 129. Aplurality of first package contacts 127 are disposed adjacent a plane126-1 defined by a first major surface 132 of the package which issubstantially parallel to the planes 116-x of the one or moremicroelectronic elements 112. A plurality of second package contacts 129of the same package 108 are disposed adjacent a plane 126-2 defined by asecond major surface 134 of the package which is substantially parallelto the planes 116-x of the one or more microelectronic elements 112.

In the embodiment depicted in FIG. 4, each of the package contacts 127,129 is disposed at a single remote surface 130 of the respective package108, and the single remote surface is defined by a vertically-orientedplane at which each package contact 127, 129 terminates, within amanufacturing tolerance. Alternatively, package contacts 127 may extendfarther in a direction parallel to plane 126-1 than the package contacts129; or the package contacts 129 may extend farther in a directionparallel to plane 126-1 than the package contacts 127. For example, thepackage contacts may project beyond the remote surface 130 a distance of50 microns or more. One or both of such features may help accommodate aparticular interconnection arrangement between the package and asubstrate electrically coupled with the package such as described belowwith reference to FIGS. 8-9.

In one example, the first package contacts 127 and the second packagecontacts 129 are portions of individual leadframe elements severed froma single common leadframe. The first package contacts can be straightleadframe elements which extend parallel to the major surface 132 of thepackage. The second package contacts can be portions of other leadframeelements which are bent relative to the major surface 132 of the packagesuch that at least one portion of the leadframe element extends in adirection at an angle to the major surface 132 of the package. In somecases, the second package contacts are terminal ends of leadframeelements 137 that have a flattened S-shape as seen in the elevationalview of FIG. 4. The leadframe elements can be formed either prior to orafter other fabrication processes used to electrically couplemicroelectronic elements in the package with the leadframe elements. Theone or more microelectronic elements in each package can be supported ona die attach pad 152, a portion of the same leadframe which provides thepackage contacts. For example, a rear surface 122 of a lowestmicroelectronic element 112 in a stack thereof can be attached to aninwardly facing major surface of the leadframe die attach pad 152.

A dielectric region 135 may overlie or contact the front and edgesurfaces of the package, and have a remote surface 130 spaced apart fromthe microelectronic element's edge surface 120 which is closest to theremote surface. In particular cases, the dielectric region can extendfrom two or more edge surfaces of the microelectronic element tocorresponding remote surfaces of the package spaced apart from the edgesurfaces. Each microelectronic element may have such dielectric regionoverlying the edge surface thereof. In an example, the dielectric region135 may be or may include a molded dielectric region. In one example,the dielectric region may comprise a polymeric dielectric material, oralternatively a polymeric dielectric material with a filler thereinwhich may have a lower coefficient of thermal expansion than thepolymeric material. In some examples, the filler may include particles,flakes or a mesh or scaffold of an inorganic material such as a glass,quartz, ceramic or semiconductor material, among others.

FIG. 4 further illustrates locking features 154, 156 which can be etchedout portions of the die attach pad 152 and the leadframe elements 137,such features serving to avoid forces acting on the die attach pad 152and the leadframe elements 137 from outside the package from loosening,pulling or ripping the leadframe elements 137 out from the encapsulationregion.

All first package contacts and second package contacts of the samepackage can be at the same remote surface 130 of the dielectric region135. The package contacts can be portions of leadframe elements 137which extend inwardly towards positions closer to edge surfaces 120 ofthe microelectronic elements in the package As seen in FIGS. 4-5, eachpackage contact can be electrically coupled with the chip contact 118 ata front surface of a microelectronic element through a wire bond 128.Wire bonds can be formed, for example, by heating an end of an extrudedwire projecting from an exposed tip of a capillary bonding tool to forma molten metal ball at the tip of the wire, and bonding the ball underheat and pressure to the chip contact. Thereafter, the tip of thebonding tool then is moved to a position at the surface of a leadframeelement 137 where the bonding tool stitch bonds a segment of the wireand then severs the bonded end of the wire to complete the process. Inone variation, a reverse wire bonding technique can be employed in whichthe wire is ball bonded to the leadframe element and then stitch bondedto the chip contact of the respective microelectronic element. In somecases, reverse wire bonding may be selected to provide wire bonds havingreduced loop height in comparison to wire bonds 128 having ball bonds onthe microelectronic elements.

Referring to FIG. 4, more than one microelectronic element can beprovided in an individual microelectronic package 108. An advantage ofproviding a plurality of microelectronic elements in the same package isa potential to increase a density of interconnection between themicroelectronic elements and a substrate 138 having a finiteinterconnection area at a major surface 142 thereof. Microelectronicpackages 108 which incorporate two microelectronic elements per packagecan be electrically interconnected with a substrate 138 at an effectivepitch which is one half a pitch of interconnection among the packagecontacts 127, 129 provided at an interconnection interface with thesubstrate 138. In a particular embodiment, when microelectronic elementsin a package 108 are microelectronic elements having memory storagearrays therein, corresponding chip contacts which on all of themicroelectronic elements in the package may be electrically coupled witha single package contact of the package. The same can apply to most orall of the chip contacts of each microelectronic element, except forchip contacts assigned to receive signals routed uniquely to one of themicroelectronic elements, such as a chip select input, for example. Thesame applies to microelectronic elements which provide non-volatilememory storage array function, such non-volatile memory storage arrayimplemented by a greater number of active devices in the microelectronicelement than for any other function of the microelectronic element.

The number of microelectronic elements stacked one above the other ineach microelectronic package can range from a small number such as oneor two to a much larger number, for example, eight, sixteen or evengreater. In the example depicted in FIGS. 3-4, four microelectronicelements can be stacked within a single package and electrically coupledwith the package contacts of such package. In another example (notshown) similar to that shown in FIG. 4, eight microelectronic elementscan be stacked within a single package and electrically coupled with thepackage contacts 127, 129 of such package.

In a variation of the structure shown in FIG. 4, other ways can beprovided for electrically coupling the microelectronic elements with theleadframe elements. For example, a conformal electrically conductivematerial can be deposited in contact with the chip contacts 118, frontsurfaces 114 and edge surfaces 120 of one or more microelectronicelements in the stack to form lines which extend from the chip contacts118 to the leadframe elements 137. In one example, the electricallyconductive material can be deposited by plating. In a particularexample, the electrically conductive material can be an electricallyconductive polymeric material or electrically conductive ink asdisclosed in U.S. Pat. No. 8,178,978, the disclosure of which isincorporated herein, and the lines of electrically conductive materialcan be formed as disclosed therein.

As particularly shown in the in-process structure seen in FIG. 5, duringfabrication of each package 108, the wire bonds 128 can be formed whilethe leadframe elements are integral portions of a leadframe, after whichan encapsulant can be applied to the in-process structure, and theleadframe can be severed where shown at the dashed line to sever theindividual leadframe elements into separate leadframe fingers havingpackage contacts at ends thereof.

Referring again to FIG. 4, all the front surfaces of each of themicroelectronic elements in the package 108 are oriented in the samedirection. In a variation of that shown in FIG. 4, the front surfaces ofone or more of the microelectronic elements in the package can beoriented in the opposite direction. In a particular embodiment, forexample, as seen in FIG. 12, the front surfaces of at least two of themicroelectronic elements which are adjacent one another may either faceeach other or face in opposite directions away from one another.

As further shown in FIG. 3, a stacked microelectronic assembly 100comprises a plurality of packages 108 having first package contacts 127and second package contacts 129 electrically coupled to substratecontacts 140 at a surface 142 of a substrate 138 through electricallyconductive masses 144 of bonding material. The substrate 138 may be adielectric element or other substrate and which may have one or multiplelayers of dielectric material and one or multiple electricallyconductive layers thereon. The substrate 138 can be formed of variousmaterials, which may or may not include a polymeric component, and mayor may not include an inorganic component. Alternatively, the substratemay be wholly or essentially polymeric or may be wholly or essentiallyinorganic. In various non-limiting examples, the support element can beformed of a composite material such as glass-reinforced epoxy, e.g.,FR-4, a semiconductor material, e.g., silicon or gallium arsenide, orglass or ceramic material.

The substrate can be one that has contacts on a lower surface facingaway from the microelectronic assemblies, the contacts configured forsurface mounting to another component which can be a card, tray,motherboard, etc., such as via a land grid array (LGA), ball grid array(BGA), or other technique. In another example, the substrate can be acard component having slide contacts on top and bottom surfaces thereof,such as for insertion into a socket. In yet another example, anothercomponent such as universal serial bus (USB) controller or othercommunications controller can be mounted to the substrate andelectrically coupled with the microelectronic assembly, such componentassisting in or controlling a flow of information between themicroelectronic assembly and a system.

As illustrated in FIG. 3, the parallel planes 116-x may be oriented in adirection orthogonal to the plane 136 of the substrate major surface,and the major surface 142 of the substrate faces the edge surfaces 120of each chip. An adhesive 146, which may be an underfill, may be appliedsurrounding the electrical connections between the leadframeinterconnects and the substrate contacts and the adhesive may have afunction to mechanically reinforce or stiffen such electricalconnections and may help the electrical connections withstand stressesdue to differential thermal expansion between the chips microelectronicelements 112 and the support element 138.

In a variation of the microelectronic assembly illustrated in FIGS. 1-4,a plurality of the package stacks 110 can be mounted and electricallyconnected to the substrate contacts 140, each package stack 110comprising a plurality of stacked microelectronic packages, such asshown, for example in FIG. 2 of U.S. application Ser. 14/883,864 filedOct. 15, 2015, the disclosure of which is incorporated herein byreference. The distance in an orthogonal direction between majorsurfaces of respective adjacent package stacks 108 defines a gap which,in some cases may be 100 microns, or may range from 100 to 200 micronsin dimension, or may have a greater value. In some cases, this gap maybe as large as 1 millimeter. Within such gap an adhesive can beprovided, and/or other elements, which may in some cases include a heatspreader as further describe below, or passive components, hardware, orother components which may or may not be electrically interconnectedwith one or more of the package stacks 110.

As further seen in FIG. 6A, in a view of a package stack 110 lookingtowards bottom surfaces of packages 108 therein which are configured tobe coupled with the substrate contacts, the first package contacts 127of microelectronic packages 108 in a package stack 110 are seen adjacenta package first major surface 132 oriented in a first direction, whilethe second package contacts 129 of the microelectronic packages 108 areadjacent a package second major surface 134 oriented in a directionopposite the first direction. The second package contacts 127 are seenaligned and adjacent with corresponding ones of the first packagecontacts, wherein the aligned and adjacent first and second packagecontacts of the immediately adjacent packages 108 may touch or may comeclose to touching. Thus, the packages can be stacked such that the firstmajor surface 132 of each next higher ordered package faces the secondmajor surface 134 of the next lower ordered package adjacent thereto,wherein the first package contacts of each next higher ordered packageare aligned with the second package contacts of the next lower orderedpackage adjacent thereto.

As further seen in FIG. 3, the aligned and adjacent first and secondpackage contacts of immediately adjacent packages 108 can beelectrically coupled with the same substrate contact. Specifically, thesame electrically conductive mass 144 may join an individual substratecontact 140 at the substrate major surface 142 with a first packagecontact 127 of one package 108 and with the aligned and adjacent secondpackage contact 127 of another package 108 immediately adjacent to suchpackage.

In the particular arrangement of FIG. 6A, each package 108 can beidentical to every other package, but some packages 108-1 have differentorientations from other package 108-2. In the example of FIG. 6A, eachpackage 108-1 is rotated 180 degrees relative to the orientation of eachpackage 108-2.

As seen in FIGS. 6B-6C, in a variation of the above-describedembodiment, each of the packages 108-1, 108-2 in the package stack 110Acan be identical to one another and have the same orientation. In thisway, second package contacts 129 of one package 108-1 which are closestto the first package contacts 127 of the adjacent package 108-2 in thepackage stack 110A are not aligned with one another. Such arrangementcan facilitate the formation of separate electrical connections betweenthese first and second package contacts 127, 129 of adjacent packages108-1, 108-2 to the substrate contacts 140, as seen, for example in FIG.6C. Optionally, as seen in FIGS. 6B-C, a spacer 109 can be positionedbetween adjacent packages 108-1, 108-2 in the package stack to provideadequate and/or optionally uniform spacing between the first packagecontacts 127 and the second package contacts 129 which are closestthereto. In a particular embodiment, the leadframe elements from whichthe package contacts are formed can be bent or placed to maintain arelatively constant pitch of the package contacts 127, 129 even betweenadjacent packages.

In the package stack 110B according to the further variation seen inFIG. 6D, the second package contacts 129 can be displaced in a directionaway from the second major surface 134 of each package 108B therein. Inone example, the leadframe elements can be bent or placed to form thesecond package contacts 129 with less separation in height from thefirst package contacts 127 of each individual package 108B. In anotherexample, the dielectric region 135, e.g., encapsulation of each package108B can be formed to a greater height than in the example shown in FIG.6A. The variation according to FIG. 6D can also facilitate the formationof separate electrical connections between first and second packagecontacts 127, 129 of adjacent packages 108-1, 108-2 and the substratecontacts 140, as seen, for example in FIG. 6C by providing increasedseparation between the first and second package contacts 127, 129 of theadjacent packages 108B seen in FIG. 6D.

In another variation seen in FIG. 7, each package has the sameorientation as every other package. However, each package 108-2 isoffset in a direction parallel to a major surface 132 of such packagefrom each package 108-1. In this case, some of the first packagecontacts 127 on a given package may not be aligned with some of thecorresponding second package contacts 129 on the package immediatelyadjacent thereto.

FIG. 8 illustrates a microelectronic assembly 200 according to aparticular embodiment in which the plane defined by the major surface134 of each package 208 therein is oriented at an acute angle 148relative to the plane 136 defined by the substrate major surface. Withpackages 208 tilted relative to the substrate, it is possible toaccommodate a same or different number of packages as in the embodimentseen in FIGS. 1-5 above, but within a shorter height 212 from the majorsurface 142 of the substrate that varies with a factor based on the sineof the angle 148. In a particular example, when the angle 148 is 45degrees, the height can be reduced by a factor based upon the sine ofthe angle (sin 45°). Thus, the height is reduced to less than theoriginal height and closer to a value that equals the sine of the angleor about 0.7 the original height. In another example, if angle 148 canbe reduced to 30 degrees, the height can be reduced by a factor based onthe sine of the angle (sin 30°), to a value that is closer to about halfthe original height. Additional reinforcing material such as underfill146 or other structure between the package stack and the substrate maybe provided to reinforce the mechanical integrity of the tiltedmicroelectronic assembly seen in FIG. 8. Although FIG. 8 indicates thefront surfaces of the stacked microelectronic elements facing or tiltingtowards the plane 136 of the major surface of the substrate 138, tilt inthe opposite direction is also possible.

Referring to FIG. 9, in a particular example of the tiltedmicroelectronic assembly, first package contacts 227 may extend fartherfrom the encapsulation in a direction parallel to the package majorsurface 134 than the second package contacts 229. In such case, thefirst package contacts 227 and second package contacts 229 may terminateat positions which intersect an interconnection plane 247 disposed at anacute angle 248 relative to the substrate major surface 132. Inparticular embodiments, the angle 248 may have the same or a differentmeasure as the angle 148. With package contacts on one side of thepackage longer than those on the other side of the package, the firstpackage contacts and the second package contacts can define a planarinterconnection interface advantageous for interconnection with thesubstrate in the tilted microelectronic assembly seen in FIG. 8. Inanother embodiment, second package contacts 229 may extend farther fromthe encapsulation in a direction parallel to the package major surface134 than the first package contacts 227.

FIG. 10 illustrates another variation in which leadframe elements 329which form the second package contacts can include only a single bend,such that the leadframe element forms a flattened L-shape rather thanthe flattened S-shape as in the above-described example.

FIG. 11 illustrates another variation of a microelectronic assembly 350in which adjacent first and second package contacts 367, 369 on eachpackage 358 therein intersect the same plane 356 parallel to an edgesurface 360 of the microelectronic assembly. Package contacts 367, 369which are adjacent one another on adjacent packages 358 may beelectrically coupled to one another by bonding material 144 thatelectrically couples the package contacts to a corresponding substratecontact 140, as seen, for example, in FIG. 3. Alternatively, packagecontacts 367, 369 which are adjacent to one another on adjacent packages358 may remain electrically separate from one another in that separatebonding material masses 144 can be used to electrically couple each ofthe adjacent package contacts 367, 369 to separate substrate contacts,similar to the example seen in FIG. 8 except that the packages can beoriented perpendicularly or at an angle relative to the major surface ofthe substrate.

FIG. 12 illustrates yet another variation in which first and secondstacks 411, 421 of microelectronic elements can be attached tooppositely facing surfaces of leadframe die attach pad therein andmicroelectronic elements are electrically coupled with first packagecontacts 427, second package contacts 429, and third package contacts431. In such case, first package contacts 427 can be disposed at acentral position of the package 408 between the planes adjacent to whichthe second package contacts 429 and third package contacts 431 aredisposed. In a particular example, the package contacts can be arrangedat bottom-facing surfaces of the package 408 in a manner as seen in FIG.13, such arrangement being similar to that described above relative toFIG. 6A except as to the particular arrangement including the additionalthird package contacts 431 and that the first package contacts aredisposed centrally. In another embodiment, only first package contact427 along with either of second package contact 429 or third packagecontact 431 would be formed.

In a particular variation seen in FIG. 14, individual stacks 510 of morethan one microelectronic package can be separated from one another byspaces 518 which accommodate other elements such as heat spreaders,other microelectronic packages or packaging structure, other integratedor discrete components such as resistors, capacitors, inductors or otherpassive or active electronic components. A further such component 520may overlie the assembly and be electrically, mechanically and/orthermally coupled to the components within the spaces between adjacentpackage stacks 510.

In one variation seen in FIGS. 15-16, first and second leadframeelements 637-1 and 637-2 can extend to and terminate in first packagecontacts 627 and second package contacts 629 which are flush with theremote surface 630 of the package within a manufacturing tolerancetherefor. In such embodiment, a compliant feature 640 may beincorporated into the package to absorb stresses due to differentialthermal expansion between the external substrate (e.g., substrate 138,FIG. 3) and the contacts of the package. FIG. 16 illustrates amicroelectronic assembly 600 which incorporates a plurality of packages608 in which the package contacts are so arranged. Although, FIG. 15depicts that first package contacts 627 and second package contacts 629are flush with the remote surface 630, they may also be recessed insidethe remote surface 630.

Although not specifically shown in the Figures or particularly describedin the foregoing, elements in the various Figures and various describedembodiments can be combined together in additional variations of theinvention.

The invention claimed is:
 1. A stacked microelectronic assembly,comprising: a plurality of stacked encapsulated microelectronic packagesstacked one above another in the stacked microelectronic assembly, eachencapsulated microelectronic package comprising: a microelectronicelement having a front surface and a plurality of edge surfacesextending away from the front surface; a plurality of remote surfacesand an encapsulation region contacting at least one edge surface of themicroelectronic element, the encapsulation region having a major surfacebeing at least substantially parallel to the front surface of themicroelectronic element; and a plurality of first electricallyconductive package contacts disposed within a first plane parallel tothe major surface, and a plurality of second electrically conductivepackage contacts disposed within a second plane parallel to the firstplane and displaced from the first package contacts, the first packagecontacts and the second package contacts being disposed at or adjacentto a single one of the remote surfaces, wherein the first packagecontacts and the second package contacts of each microelectronic packageface and are electrically coupled with respective sets of firstsubstrate contacts and second substrate contacts at a major surface of asubstrate via an electrically conductive bonding material, the majorsurface oriented non-parallel with the front surfaces of themicroelectronic elements, each set of first substrate contacts joinedwith the first package contacts of only one of the microelectronicpackages, and each set of second substrate contacts joined with thesecond package contacts of only the one of the microelectronic packages.2. The stacked microelectronic assembly as claimed in claim 1, whereinthe front surfaces of the microelectronic elements in each of theplurality of microelectronic packages are parallel with one another. 3.The stacked microelectronic assembly as claimed in claim 1, wherein themajor surface of each microelectronic package is a first major surface,the encapsulation region of each microelectronic package having a secondmajor surface opposite the corresponding first major surface and beingat least substantially parallel to the front surface of thecorresponding microelectronic element.
 4. The stacked microelectronicassembly as claimed in claim 3, wherein the second major surface of eachmicroelectronic package extends within the second plane of thecorresponding microelectronic package.
 5. The stacked microelectronicassembly as claimed in claim 3, wherein the second plane of eachmicroelectronic package is displaced from the second major surface ofthe corresponding microelectronic package in a direction orthogonal tothe corresponding second major surface.
 6. The stacked microelectronicassembly as claimed in claim 1, wherein each microelectronic package hasa same rotational orientation with respect to the other ones of themicroelectronic packages.
 7. The stacked microelectronic assembly asclaimed in claim 1, wherein each of the first package contacts and thesecond package contacts of each package is a portion of a firstleadframe element or a portion of a second leadframe element,respectively, of a common leadframe, the second leadframe elementshaving first portions interdigitated among neighboring first leadframeelements, the second package contacts being remote from the firstportions and remote from the first leadframe elements.
 8. The stackedmicroelectronic assembly as claimed in claim 7, wherein the secondleadframe elements of at least one of the packages have bends betweenthe first portions and the second package contacts.
 9. The stackedmicroelectronic assembly as claimed in claim 7, wherein the commonleadframe of at least one of the packages further comprises a die attachpad, wherein the microelectronic element has a face bonded to the dieattach pad.
 10. A stacked microelectronic assembly, comprising: aplurality of stacked encapsulated microelectronic packages stacked oneabove another in the stacked microelectronic assembly, each encapsulatedmicroelectronic package comprising: a microelectronic element having afront surface and a plurality of edge surfaces extending away from thefront surface; a plurality of remote surfaces, and an encapsulationregion contacting at least one edge surface of the microelectronicelement, the encapsulation region having first and secondoppositely-facing major surfaces, each major surface being at leastsubstantially parallel to the front surface of the microelectronicelement; and a plurality of first electrically conductive packagecontacts disposed within a first plane parallel to the first majorsurface and a plurality of second electrically conductive packagecontacts disposed within a second plane parallel to the first plane anddisplaced from the first package contacts, the first package contactsand the second package contacts being disposed at or adjacent to asingle one of the remote surfaces, the plurality of second electricallyconductive package contacts being displaced from the second majorsurface in a direction orthogonal to the second major surface.
 11. Thestacked microelectronic assembly as claimed in claim 10, wherein thefirst package contacts and the second package contacts of each packagein the stacked assembly face and are electrically coupled withcorresponding substrate contacts at a major surface of a substrateexternal to the encapsulation regions of each microelectronic package ofthe stacked microelectronic assembly, the major surface orientednon-parallel with the front surfaces of the microelectronic elements inthe stacked microelectronic assembly.
 12. The stacked microelectronicassembly as claimed in claim 11, wherein the substrate contacts comprisea plurality of sets of substrate contacts, each set comprising aplurality of the first substrate contacts joined with the first packagecontacts of only one of the microelectronic packages via an electricallyconductive bonding material, and a plurality of second substratecontacts joined with the second package contacts of only the one of themicroelectronic packages via an electrically conductive bondingmaterial.
 13. The stacked microelectronic assembly as claimed in claim10, wherein each microelectronic package has a same rotationalorientation with respect to the other ones of the microelectronicpackages.
 14. An encapsulated microelectronic package, comprising: amicroelectronic element having a front surface and a plurality of edgesurfaces extending away from the front surface; a plurality of remotesurfaces, and an encapsulation region contacting at least one edgesurface of the microelectronic element, the encapsulation region havingfirst and second oppositely-facing major surfaces, each major surfacebeing at least substantially parallel to the front surface of themicroelectronic element; and a plurality of first electricallyconductive package contacts disposed within a first plane parallel tothe first major surface and a plurality of second electricallyconductive package contacts disposed within a second plane parallel tothe first plane and displaced from the first package contacts, the firstpackage contacts and the second package contacts being disposed at oradjacent to a single one of the remote surfaces, the plurality of secondelectrically conductive package contacts being displaced from the secondmajor surface in a direction orthogonal to the second major surface. 15.The microelectronic package as claimed in claim 14, wherein each of thefirst package contacts and the second package contacts of each packageis a portion of a first leadframe element or a portion of a secondleadframe element, respectively, of a common leadframe, the secondleadframe elements having first portions interdigitated amongneighboring first leadframe elements, the second package contacts beingremote from the first portions and remote from the first leadframeelements.
 16. The microelectronic package as claimed in claim 15,wherein the second leadframe elements of at least one of the packageshave bends between the first portions and the second package contacts.17. The microelectronic package as claimed in claim 15, wherein thecommon leadframe further comprises a die attach pad, wherein themicroelectronic element has a face bonded to the die attach pad.
 18. Themicroelectronic package as claimed in claim 17, wherein themicroelectronic element comprises first and second microelectronicelements, the faces of the first and second microelectronic elementsoverlying and mechanically coupled with a first surface of the dieattach pad.
 19. The microelectronic package as claimed in claim 15,wherein the second leadframe elements protrude beyond a surface of theencapsulation region by more than 50 microns.
 20. The microelectronicpackage as claimed in claim 14, wherein the plurality of first stackedmicroelectronic elements are stacked such that an edge surface of eachfirst stacked microelectronic element is offset in a directionperpendicular to the edge surface from the edge surface of each firststacked microelectronic element that is immediately beneath such firststacked microelectronic element, and the plurality of first stackedmicroelectronic elements are electrically coupled with the first packagecontacts and the second package contacts via wire bonds.